Do web comics seem to be the next evolution in sequential art or is this just a fad that will fade?
I don't believe it's a fad; just a different outlet or tool that people can use now. And as the blogosphere has shown, self-publishing/producing is nearly ubiquitous now -- everyone has a voice/vision/vaticination that can be shared with everyone else now, with varying degrees of success (in both the popular and qualitative sense of the word).
Since it's been around for a while, I think it's past the awkward "online n00b" phase of just throwing crap to the virtual wall to see what sticks (though there's plenty of that, too -- but really no different than the music or videos or games that are clogging up our collective bandwidth) and you're seeing both high quality work and creators willing to push the medium in new directions.
There's plenty of room for both for me and it's actually interesting to see them crossover a bit.